Anything you say CAN and WILL be used against you. Even if your doing nothing wrong they will twist it to their narrative...so give them nothing

You may have nothing to hide today but if you can't defend yourself tomorrow, they will kill you and your entire family.

The police recomend you hide your belongings when you leave you car. So you should probably reconsider that.

"Unlock your phone and give it to me"

ask them if they would say the same to an activist from an oppressive country

Inform them that privacy is not secrecy.

"Yeah, I know what you do on the toilet, but don't you still close the door?"

It is important to recognize that Privacy is a human right, and without it we cannot reasonably express ourselves and potentially democracies could be threatened too. With our right to Privacy not always being upheld, we need to take matters into our own hands where reasonable and push back.

Edit: not to mention that anything we do now may become illegal five minutes from now. Nowadays we cannot know.

"Do you like anal?"

I bet a lot of people would suddenly have something to hide.

Ok Mr. Trump, good deal. Yeh talked me into it

I say that they're mind set while fine for them will negatively effect society. This often turns into a tangent.

I will also ask them for they're personal and work emails to log in.

Lot of folks here making the "nothing to hide? Great show me your browsing history" type arguments.

I think this isn't really arguing in good faith. There's a big difference between a personal friend knowing something about you, and a faceless algorithm knowing something about you. The two cases are different; it's fair to argue about how one is better or worse, but they are different.

That can change in an instant if the government ever decides to outlaw something you aren't hiding.